xen: Use MaxInt32 rather than MaxInt64 for internal version of 'master'

We currently use MaxInt64 as the "version number" for 'master' internally so that 'master'
always compares as "greater than" all normal Xen versions.  Unfortunately,
on 32-bit builds 'int' is only 32 bits, so building results in the following
error:

./xen.go:22:3: constant 9223372036854775807 overflows int

The 'math' package doesn't contain a MaxInt (which is why it was
MaxInt64 in the first place); but MaxInt32 will be fit for purpose for
both architectures.  At such time as Xen's major number exceeds 2
billion, we can deprecate the 32-bit build of this tool.

The other option would have been to use code from this template to
calculate MaxInt at compile time:

https://groups.google.com/forum/#!msg/golang-nuts/a9PitPAHSSU/ziQw1-QHw3EJ

But I think that would have been a bit overkill.

Signed-off-by: George Dunlap <george.dunlap@citrix.com>

diff --git a/xen.go b/xen.go
index e14694970151e95276ddc233c405ff7e3c63fcaa..ff4c2c404515d5995d83ccdbebfb75ba43b64a99 100644 (file)
--- a/xen.go
+++ b/xen.go
@@ -19,7 +19,9 @@ func (v XenVersion) String() string {
 
 func (v XenVersion) parse() (major, minor int, err error) {
        if v == "master" {
-               return math.MaxInt64, 0, nil
+               // NB if Xen's major ever exceeds 2 billion, we'll
+               // need to deprecate the 32-bit build of this tool.
+               return math.MaxInt32, 0, nil
        }
 
        major = -1
@@ -33,9 +35,18 @@ func (v XenVersion) parse() (major, minor int, err error) {
        }
 
        major, err = strconv.Atoi(submatch[1])
-       if err == nil {
-               minor, err = strconv.Atoi(submatch[2])
+       if err != nil {
+               return
        }
+
+       if major > math.MaxInt32 {
+               err = fmt.Errorf("Version too large")
+               major = -1
+               return
+       }
+
+       minor, err = strconv.Atoi(submatch[2])
+
        return
 }
 
@@ -89,7 +100,7 @@ func (v XenVersion) IsGreaterThan(v2 XenVersion) bool {
        return v.gt(v2, false)
 }
 
-func (v XenVersion) PrevVersion() (next XenVersion, err error) {
+func (v XenVersion) PrevVersiongit () (next XenVersion, err error) {
        major, minor, err := v.parse()
        if err != nil {
                err = fmt.Errorf("Parsing version %v: %v\n", v, err)